Biotin is a vitamine useful as an additive for feed, medicine, etc., and as a process for preparing the same, it has been known a process, for example, in which a thienoimidazol compound represented by the following formula:
is used as a synthetic intermediate (Chemical Reviews, vol. 97, No. 6, pp. 1755-1792, 1997, Japanese Patent Publications No. Sho. 49-32551 and Sho. 53-27279, Japanese Patent Publications No. Hei. 3-66312 and Hei. 5-9064) and the like.
However, these conventionally known processes involve the problems that its preparation steps are long, and they require complicated optical resolution in the course of the preparation steps.
An object of the present invention is to provide a process for preparing biotin which is industrially advantageous.